Ce(SO4)2-mediated nitration of N,N-dialkylanilines with NaNO2 in water

Article abstract of DOI:10.1080/00397910701484025

Ce(SO4)2-mediated nitration of N,N-dialkylanilines with NaNO2 using water as the solvent has been achieved in good to excellent yields. The nitrating reaction proceeded smoothly at ambient temperature. Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/00397910701484025

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Ce(SO4)2‐Mediated Nitration of
N,N‐Dialkylanilines with NaNO2 in Water
Xianghua Yang a & Chanjuan Xi a
a Key Laboratory for Bioorganic Phosphorus Chemistry and Chemical Biology
(Ministry of Education), Department of Chemistry , Tsinghua University ,
Beijing, China
Published online: 05 Oct 2007.
To cite this article: Xianghua Yang & Chanjuan Xi (2007) Ce(SO4)2‐Mediated Nitration of N,N‐Dialkylanilines
with NaNO2 in Water, Synthetic Communications: An International Journal for Rapid Communication of
Synthetic Organic Chemistry, 37:19, 3381-3392, DOI: 10.1080/00397910701484025
To link to this article: http://dx.doi.org/10.1080/00397910701484025
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Synthetic Communicationsw, 37: 3381–3392, 2007
Copyright # Taylor & Francis Group, LLC
ISSN 0039-7911 print/1532-2432 online
DOI: 10.1080/00397910701484025
Ce(SO4)2-Mediated Nitration
of N,N-Dialkylanilines with NaNO2 in Water
Xianghua Yang and Chanjuan Xi
Key Laboratory for Bioorganic Phosphorus Chemistry and Chemical
Biology (Ministry of Education), Department of Chemistry, Tsinghua
University, Beijing, China
Abstract: Ce(SO4)2-mediated nitration of N,N-dialkylanilines with NaNO2 using
water as the solvent has been achieved in good to excellent yields. The nitrating
reaction proceeded smoothly at ambient temperature.
Keywords: Ce(SO4)2, N,N-dialkylarylamine, NaNO2, nitration, water
Nitroaromatic compounds, as an important class of chemical feedstock, are
broadly employed in many industrial fields and demanded in huge amounts.
The conventional procedure for nitration of aromatic compounds typically
requires a mixture of concentrated or fuming nitric acid with sulfuric acids,
leading to excessive acid waste streams and added expense.[1] Recently,
some efficient procedures for nitration of aromatic compounds have been
reported [e.g., using nitrate salts as nitrating reagents, such as VO(NO3)3,[2]
Fe(NO3)3 9H2O,[3] Bi(NO3)3 5H2O,[4] and Ce(NH4)2(NO3)6].[5] These pro-
cedures still require acidic conditions and/or organic solvents, which are often
costly, inflammable, explosive, and carcinogenic. Consequently, a nitrating
strategy without acid and organic solvent has been greatly desired.
Recently, water-mediated organic reactions have attracted increasing
interest[6] both in the laboratory and industry because water is much more
economical and safer than the usual organic solvents.
.
.
Received December 12, 2006
Address correspondence to Chanjuan Xi, Key Laboratory for Bioorganic Phos-
phorus Chemistry and Chemical Biology (Ministry of Education), Department of
Chemistry, Tsinghua University, Beijing 100084, China. E-mail: cjxi@tsinghua.edu.cn
3381

3382
X. Yang and C. Xi
Scheme 1.
Herein, we report a mild nitrating system for N,N-dialkylanilines, using
sodium nitrite and ceric sulfate with water as the solvent, which needs neither
acidic conditions nor organic solvent and is quite easy to handle (Scheme 1).
To start, experiments were carried out to select the reaction condition. The
representative results for the nitration of 1 mmol of N,N-diethylaniline (1a)
mediated by various amount of NaNO2 and Ce(SO4)2 are summarized in
Table 1. First, different ratios of NaNO2 and Ce(SO4)2 were tested (Table 1,
entries 1–6), and the ratio of NaNO2/Ce(SO4)2 ¼ 10:1.5 was found to work
best. Under this condition, the isolated yields of ortho- and para-nitrated
products were 28% and 54%, respectively (entry 4). When the amount of
Ce(SO4)2 increased to 2 equiv (entry 5), mononitrated products 2a and 3a
formed together with some multinitroproducts (e.g., N,N-diethyl-2,4-dinitroani-
line and N,N-diethyl-2,4,6-trinitroaniline). When Ce(SO4)2 was absent in the
system (entry 7), the reaction did not proceed. When the reaction was treated
in the absence of NaNO2 (entry 8), a homocoupling product was observed.[7]
Table 1. Nitration of N,N-diethylaniline with various amounts of ceric sulfate and
sodium nitrite
Entry
NaNO2 (mmol) Ce(SO4)2 (mmol) Yield of 2a (%)a Yield of 3a (%)a
1
5
10
15
10
10
10
10
0
1
21
6
26
48
2
1
3
1
27
28
11
Trace
0
36
54
4
1.5
2
5b
6
34
Trace
0
0.1
0
7
8c
2
0
0
aIsolated yield based on substrates.
bOvernitrated products were found.
cPara, para-coupling product was isolated in 71% yield.

Nitration of N,N-Dialkylanilines
3383
Various N,N-dialkylanilines were allowed to react with NaNO2 and Ce(SO4)2
under the optimized condition. The results are summarized in Table 2. When
N,N-dialkylanilines such as 1a–f (entries 1–6) were used, both ortho- and
para-nitrated products were obtained in good yield, and the para-nitro product
was always the major one. When N,N-dialkylanilines were substituted on the
ortho-position (e.g., N,N-diethyl-2-methylaniline 1g and 2-chloro-N,N-diethyla-
niline 1h, no target products were detected (entries 7 and 8). It might be attributed
to the hindrance of the substitute on the ortho-position. As for the meta-substituted
Table 2. Nitration of N,N-dialkylanilines in watera
Entry
1
Substrates
Yieldb of 2
2a (28)
Yieldb of 3
3a (54)
2
3
2b (35)
2c (37)
3b (49)
3c (42)
4
5
2d (34)
2e (25)
3d (43)
3e (52)
6
7
2f (17)
2g (0)
3f (69)
3g (0)
8
9
2h (0)
3h (0)
3i (42)
3j (60)
2ic (32)
2jc (24)
10
aWith the molar ratio of substrates/Ce(SO4)2/NaNO2 ¼ 1:1:10.
bIsolated yield based on substrates.
cMixture product of nitration on both ortho-positions.

3384
X. Yang and C. Xi
substrates, such as 1i and 1j, ortho- and para-nitrated products were obtained, and
nitrating happened at both ortho-positions (entries 9 and 10). It is worth noting that
in all cases, the two regioisomers could be easily separated from each other by
column chromatography on Al2O3.
With para-substituted substrates, only the ortho-nitrated product was
obtained in excellent yield. The results are summarized in Table 3. In these
cases, 2 equiv of Ce(SO4)2 are suitable to achieve high isolated yield
without any by-product.
Table 3. Nitration of N,N-dialkylanilines in watera
Entry
1
Substrate
Product
Yield (%)b
99
2
3
4
5
6c
7
8
88
82
98
99
86
86
85
aWith the ratio of substrates/NaNO2/Ce(SO4)2 ¼ 1:10:2 in 20 mL of H2O.
bIsolated yield based on subatrates.
bReaction proceeded at 508C.

Nitration of N,N-Dialkylanilines
3385
Scheme 2.
For this nitrating process, a radical attacking mechanism was proposed, as
shown in Scheme 2. In the beginning, NO2 which was reported as a radical
reagent,[8,9] was generated by reaction of Ce(SO4)2 and NaNO2. Then, the
Ce(IV), or the NO2 molecule, attracted a single electron from the nitrogen
atom of aniline and gave the radical cation 4, which can be expressed as
another two resonance structures, 5 and 6. Subsequently, another NO2
molecule attacked the intermediates 5 and 6, and final products 2 and 3
were afforded after deprotonation.
To confirm the reaction mechanism, an experiment was carried out in a
sealed system. The system included two vessels connected by a glass pipe:
one vessel contained an aqueous solution of NaNO2 and Ce(SO4)2 for gener-
ation of NO2, and the other contained a solution of the substrate. The first
vessel was heated up to 508C to accelerate the generating rate of NO2. Then
the generated NO2 was piped deep into the other vessel and stirred for an
hour. o-Nitrated product was obtained with isolated yield of 69%
(Scheme 3). This result indicated that the nitration could be carried out
Scheme 3.

3386
X. Yang and C. Xi
via an NO2 attacking path. On the other hand, the formation of N,N,N0,
N0-tetraethylbenzidine in the absence of NaNO2 (Table 1, entry 8) further
proved the existence of radical cation. It is reasonable that in the presence
of NaNO2, compounds 5 and 6 could be trapped by NO2 to result in
formation of nitroaromatic compounds.
In summary, we have successfully achieved the nitration of N,N-dialkyla-
nilines in aqueous solution of NaNO2 and Ce(SO4)2. This reaction performed
in water provides a simple, practical, and eco-friendly method to prepare a
variety of nitroanilines.
EXPERIMENTAL
General Consideration
1H and 13C NMR spectra were recorded at 300 MHz and 75 MHz, respect-
ively. Chemical shift values were given in parts per million (ppm) relative
to internal Me4Si (for 1H NMR: d 0.00) and CDCl3 (for 13C NMR: d
77.16). As for starting materials, some substrates (1a, 1e, and 1g), NaNO2,
Ce(SO4)2, and all presubstrates (substituted anilines for further alkylation)
were commercial available. Other substrates were made in the laboratory
according to the literature. Substituted N,N-dimethylanilines (1l–1n) were
synthesized with the method reported by Billman et al.,[10a] others (1b–1d,
1f, 1h–1k and 1o–1r) were synthesized as Srivastava et al. reported.[11]
Representative Procedure for Nitration of N,N-Dialkylanilines
(1a–j) with N,N-Diethylaniline (1a) as the Example
NaNO2 (690 mg, 10 mmol), Ce(SO4)2 (606 mg, 1.5 mmol), and 1a (159 mL,
1 mmol) were added in sequence to an open vessel containing 20 mL of
water. The reaction mixture was stirred at room temperature for 1 h before
being quenched with aqueous K2CO3, and the organic phase was then
extracted with EtOAc. Then the solvent was evaporated under reduced
pressure. The residue was isolated by chromatography on a basic Al2O3
column, first using ethyl acetate and petroleum ether (1:200) as eluent to
get N,N-diethyl-2-nitrobenzenamine (2a, red oil) in 28% (55 mg), then
using ethyl acetate and petroleum ether (1:50) as eluent to get N,N-diethyl-
4-nitrobenzenamine (3a, yellow oil) in 54% (105 mg).
Data
N,N-Diethyl-2-nitrobenzenamine (2a).[12] Isolated as red oil, 55 mg, 28%.
1H NMR (300 MHz, CDCl3)
d
7.65 (d, J ¼ 9.96 Hz, 1H), 7.40

Nitration of N,N-Dialkylanilines
3387
(t, J ¼ 7.56 Hz, 1H), 7.13 (d, J ¼ 7.20 Hz, 1H), 6.94 (t, J ¼ 7.56 Hz, 1H),
3.14 (q, J ¼ 7.05 Hz, 4H), 1.07 (t, J ¼ 6.87 Hz, 6H), 13C NMR (75 MHz,
CDCl3) d 144.6, 144.2, 132.6, 125.6, 122.6, 120.6, 46.8, 12.7; ESI-MS:
M þ Hþ (m/z) 195.
N,N-Diethyl-4-nitrobenzenamine (3a).[13] Isolated as yellow oil, 105 mg,
54%. 1H NMR (300 MHz, CDCl3) d 8.05 (d, J ¼ 9.60 Hz, 2H), 6.54
(d, J ¼ 9.27 Hz, 2H), 3.42 (q, J ¼ 7.20 Hz, 4H), 1.19 (t, J ¼ 7.20 Hz, 6H);
13C NMR (75 MHz, CDCl3) d 152.3, 136.2, 126.5, 109.9, 45.0, 12.4; ESI-
MS: M þ Hþ (m/z) 195.
N-Butyl-N-methyl-2-nitrobenzenamine (2b).[14] Isolated as red oil, 72 mg,
35%. 1H NMR (300 MHz, CDCl3) d 7.71 (d, J ¼ 8.25 Hz, 1H), 7.36
(q, J ¼ 7.23 Hz, 1H), 7.05 (d, J ¼ 8.25 Hz, 1H), 6.81 (q, J ¼ 8.22 Hz, 1H),
3.14 (t, J ¼ 7.26 Hz, 2H), 2.80 (s, 3H), 1.60–1.51 (m, 2H), 1.34–1.25
(m, 2H), 0.90 (t, J ¼ 7.20 Hz, 3H); 13C NMR (75 MHz, CDCl3) d 146.0,
140.4, 133.1, 126.6, 119.5, 118.3, 54.4, 40.2, 29.4, 20.1, 14.0. ESI-MS:
M þ Hþ (m/z) 209.
N-Butyl-N-methyl-4-nitrobenzenamine (3b).[15] Isolated as yellow oil,
1
101 mg, 49%. H NMR (300 MHz, CDCl3) d 8.05 (d, J ¼ 8.22 Hz, 2H),
6.55 (d, J ¼ 8.58 Hz, 2H), 3.39 (t, J ¼ 7.56 Hz, 2H), 3.03 (s, 3H), 1.62–
1.53 (m, 2H), 1.40–1.29 (m, 2H), 0.94 (t, J ¼ 7.38 Hz, 3H); 13C NMR
(75 MHz, CDCl3) d 153.5, 136.5, 126.3, 110.1, 52.4, 38.8, 29.0, 20.2, 14.0.
ESI-MS: M þ Naþ (m/z) 231.
N-Ethyl-N-methyl-2-nitrobenzenamine (2c).[9f] Isolated as red oil, 66 mg,
37%: 1H NMR (300 MHz, CDCl3) d 7.70 (d, J ¼ 7.89 Hz, 1H), 7.37
(t, J ¼ 7.89 Hz, 1H), 7.05 (d, J ¼ 7.89 Hz, 1H), 6.82 (t, J ¼ 7.89 Hz, 1H),
3.19 (q, J ¼ 7.10 Hz, 2H), 2.79 (s, 3H), 1.18 (t, J ¼ 7.21 Hz, 3H); 13C
NMR (75 MHz, CDCl3) d 145.9, 140.8 133.1, 126.6, 119.6, 118.6, 49.5,
39.2, 12.4; ESI-MS: M þ Hþ (m/z) 181.
N-Ethyl-N-methyl-4-nitrobenzenamine (3c).[9f] Isolated as yellow oil,
1
76 mg, 42%. H NMR (300 MHz, CDCl3) d 8.08 (d, J ¼ 9.27 Hz, 2H), 6.57
(d, J ¼ 9.63 Hz, 2H), 3.48 (q, J ¼ 7.20 Hz, 2H), 3.04 (s, 3H), 1.19
(t, J ¼ 7.20 Hz, 3H); 13C NMR (75 MHz, CDCl3) d 153.3, 136.6, 126.4,
110.2, 47.0, 37.9, 11.7; ESI-MS: M þ Hþ (m/z) 181.
1
1-(2-Nitrophenyl)piperidine (2d).[16] Isolated as red oil, 71 mg, 34%. H
NMR (300 MHz, CDCl3) d 7.74 (d, J ¼ 8.25 Hz, 1H), 7.43 (t, J ¼ 7.89 Hz,
1H), 7.11 (d, J ¼ 8.25 Hz, 1H), 6.95 (t, J ¼ 7.72 Hz, 1H), 3.01
(t, J ¼ 5.16 Hz, 4H), 1.75–1.68 (m, 4H), 1.62–1.55 (m, 2H); 13C NMR

3388
X. Yang and C. Xi
(75 MHz, CDCl3) d 147.1, 142.7, 133.5, 126.1, 120.9, 120.7, 53.0, 26.1, 24.1;
ESI-MS: M þ Hþ (m/z) 207.
1-(4-Nitrophenyl)piperidine (3d).[17a,17b] Isolated as yellow oil, 88 mg, 43%.
1H NMR (300 MHz, CDCl3)
d
8.06 (d, J ¼ 9.27 Hz, 2H), 6.75
(d, J ¼ 9.63 Hz, 2H), 3.42 (s, 4H), 1.67 (s, 6H); 13C NMR (75 MHz,
CDCl3) d 155.0, 137.4, 126.2, 112.3, 48.4, 25.4, 24.3; ESI-MS: M þ Hþ
(m/z) 207.
N,N-Dimethyl-2-nitrobenzenamine (2e).[18] Isolated as red oil, 42 mg, 25%.
1H NMR (300 MHz, CDCl3) d 7.76 (d, J ¼ 8.25 Hz, 1H), 7.39 (t, J ¼ 8.25 Hz,
1H), 7.02 (d, J ¼ 8.25 Hz, 1H), 6.81 (t, J ¼ 8.25 Hz, 1H), 2.89 (s, 6H); 13C
NMR (75 MHz, CDCl3) d 146.4, 133.4, 129.6, 126.9, 118.2, 118.0, 42.6;
ESI-MS: M þ Hþ (m/z) 167.
N,N-Dimethyl-4-nitrobenzenamine (3e).[19] Isolated as yellow oil, 87 mg,
52%. 1H NMR (300 MHz, CDCl3) d 8.09 (d, J ¼ 9.60 Hz, 2H), 6.57
(d, J ¼ 9.60 Hz, 2H), 3.09 (s, 6H); 13C NMR (75 MHz, CDCl3) d 154.3,
137.0, 126.2, 110.3, 40.3; ESI-MS: M þ Hþ (m/z) 167.
N-Allyl-N-methyl-2-nitrobenzenamine (2f). Isolated as red oil, 33 mg, 17%.
1H NMR (300 MHz, CDCl3) d 7.73 (d, J ¼ 8.25 Hz, 1H), 7.38 (t, J ¼ 8.22 Hz,
1H), 7.05 (d, J ¼ 8.58 Hz, 1H), 6.85 (t, J ¼ 8.25 Hz, 1H), 5.81–5.92 (m, 1H),
5.19–5.24 (m, 2H), 3.75 (d, J ¼ 5.82 Hz, 2H), 2.80 (s, 3H), 13C NMR
(75 MHz, CDCl3) d 159.8, 145.7, 133.4, 133.2, 126.6, 119.8, 118.8, 118.1,
57.8, 39.6; ESI-MS: M þ Naþ (m/z) 215.
N-Allyl-N-methyl-4-nitrobenzenamine (3f). Isolated as yellow oil, 133 mg,
69%. 1H NMR (300 MHz, CDCl3) d 8.08 (d, J ¼ 9.27 Hz, 2H), 6.59
(d, J ¼ 9.27 Hz, 2H), 5.76–5.86 (m, 1H), 5.08–5.22 (m, 2H), 4.02 (s, 2H),
3.07 (s, 3H); 13C NMR (75 MHz, CDCl3) d 153.8, 137.2, 131.6, 126.2,
116.9, 110.5, 54.9, 38.6; ESI-MS: M þ Naþ (m/z) 215.
N,N-Diethyl-3-methyl-4-nitrobenzenamine (3i).[20] Isolated as yellow oil,
1
87 mg, 42%. H NMR (300 MHz, CDCl3) d 8.08 (d, J ¼ 9.60 Hz, 1H), 6.45
(d, J ¼ 9.27 Hz, 1H), 6.37 (s, 1H), 3.41 (q, J ¼ 7.20 Hz, 4H), 2.63 (s, 3H),
1.2 (t, J ¼ 7.23 Hz, 6H); 13C NMR (75 MHz, CDCl3) d 151.3, 138.0, 136.7,
128.5, 113.2, 108.6, 44.8, 23.2, 12.6. ESI-MS: M þ Hþ (m/z) 209.
3-Chloro-N,N-diethyl-4-nitrobenzenamine (3j). Isolated as yellow oil,
137 mg, 60%. 1H NMR (300 MHz, CDCl3) d 1.19(t, J ¼ 7.23 Hz, 6H),
3.39(q, J ¼ 7.23 Hz, 4H), 6.47(d, J ¼ 9.63 Hz, 1H), 6.58(s, 1H),
7.99(d, J ¼ 9.63 Hz, 1H); 13C NMR (75 MHz, CDCl3) d 12.3, 134.3, 45.0,
108.9, 112.7, 129.1, 130.9, 151.4.

Nitration of N,N-Dialkylanilines
3389
Representative Procedure for Nitration of 4-Substituted-N,N-
dialkylanilines (1k–r) with N,N-Diethyl-4-methylaniline (1k)
as the Example
NaNO2 (690 mg, 10 mmol), Ce(SO4)2 (808 mg, 2 mmol), and 1k (174 mL,
1 mmol) were added in sequence to an open vessel containing 20 mL water.
The reaction mixture was stirred at room temperature for 1 h before being
quenched with aqueous K2CO3, and the organic phase was extracted with
EtOAc. Then the solvent was evaporated under reduced pressure. The
residue was isolated by chromatography on a basic Al2O3 column, first
using ethyl acetate and petroleum ether (1:200) as eluent to get N,N-diethyl-
4-methyl-2-nitrobenzenamine (2k, red oil) in 99% (206 mg).
Data
N,N-Diethyl-4-methyl-2-nitrobenzenamine (2k). Isolated as red oil,
206 mg, 99%. 1H NMR (300 MHz, CDCl3) d 7.41 (s, 1H), 7.21
(d, J ¼ 8.25 Hz, 1H), 7.07 (d, J ¼ 8.25 Hz, 1H), 3.06 (q, J ¼ 7.23 Hz, 4H),
2.30 (s, 3H), 1.02 (t, J ¼ 7.23 Hz, 6H); 13C NMR (75 MHz, CDCl3) d
145.6, 142.0, 133.2, 131.8, 125.0, 123.4, 47.4, 20.3, 12.7; ESI-MS: M þ Hþ
(m/z) 209.
N,N,4-Trimethyl-2-nitrobenzenamine (2l).[21,22] Isolated as red oil, 159 mg,
88%. 1H NMR (300 MHz, CDCl3) d 7.49 (s, 1H), 7.15 (d, J ¼ 10.32 Hz, 1H),
6.89 (d, J ¼ 11.91 Hz, 1H), 2.77 (s, 6H), 2.22 (s, 3H); 13C NMR (75 MHz,
CDCl3) d 144.2, 139.6, 134.1, 128.2, 126.2, 118.4, 42.6, 19.8; ESI-MS:
M þ Hþ (m/z) 181.
4-Methoxy-N,N-dimethyl-2-nitrobenzenamine (2m).[22,23] Isolated as red
1
oil, 161 mg, 82%. H NMR (300 MHz, CDCl3) d 7.22 (s, 1H), 7.00 (s, 2H),
3.73 (s, 3H), 2.74 (s, 6H); 13C NMR (75 MHz, CDCl3) d 152.8, 141.2,
141.1, 120.9, 120.8, 109.6, 55.8, 43.5; ESI-MS: M þ Hþ (m/z) 197.
4-Chloro-N,N-dimethyl-2-nitrobenzenamine (2n).[22] Isolated as red oil,
196 mg, 98%. 1H NMR (300 MHz, CDCl3) d 7.69 (s, 1H), 7.27
(d, J ¼ 8.91 Hz, 1H), 6.92 (d, J ¼ 8.94 Hz, 1H), 2.84 (s, 6H); 13C NMR
(75 MHz, CDCl3) d 144.9, 138.7, 133.2, 126.1, 122.2, 119.3, 42.4; ESI-MS:
M þ Hþ (m/z) 201.
N,N-Dibutyl-4-methyl-2-nitrobenzenamine (2o). Isolated as red oil,
262 mg, 99%. 1H NMR (300 MHz, CDCl3) d 7.45 (s, 1H), 7.21
(d, J ¼ 8.22 Hz, 1H), 7.06 (d, J ¼ 8.58 Hz, 1H), 3.01 (t, J ¼ 7.40 Hz, 4H),
2.30 (s, 3H), 1.39–1.49 (m, 4H), 1.22–1.31 (m, 4H), 0.85 (t, J ¼ 7.21 Hz,
6H); 13C NMR (75 MHz, CDCl3) d 144.4, 142.9, 133.4, 130.8, 125.4,

3390
X. Yang and C. Xi
123.0, 53.0, 29.8, 20.4, 20.3, 14.0; ESI-MS: M þ Hþ (m/z) 265. Anal. calcd.
for C15H24N2O2: C, 68.15; H, 9.15; N, 10.60. Found: C, 68.40; H, 9.05; N,
10.67.
N,N-Dibenzyl-4-methyl-2-nitrobenzenamine (2p). Isolated as red oil,
284 mg, 86%. 1H NMR (300 MHz, CDCl3) d 7.54 (s, 1H), 7.26–7.35
(m, 10H), 7.18 (d, J ¼ 8.25 Hz, 1H), 7.07 (d, J ¼ 8.25 Hz, 1H), 4.24
(s, 4H), 2.31 (s, 3H); 13C NMR (75 MHz, CDCl3) d 145.0, 142.1, 137.4,
133.3, 132.5, 128.5, 128.4, 127.3, 125.3, 123.9, 57.2, 20.3; ESI-MS:
M þ Naþ (m/z) 355. Anal. calcd. for C21H20N2O2: C, 75.88; H, 6.06; N,
8.43. Found: C, 75.76; H, 6.03; N, 8.51.
N,N-Diallyl-4-methyl-2-nitrobenzenamine (2q). Isolated as red oil, 200 mg,
86%. 1H NMR (300 MHz, CDCl3) d 7.47 (s, 1H), 7.20 (d, J ¼ 8.25 Hz, 1H),
7.04 (d, J ¼ 8.25 Hz, 1H), 5.71–5.83 (m, 2H), 5.09–5.19 (m, 4H), 3.67
(d, J ¼ 5.85 Hz, 4H), 2.29 (s, 3H); 13C NMR (75 MHz, CDCl3) d 144.0,
142.0, 134.2, 133.4, 131.5, 125.4, 123.3, 118.1, 55.6, 20.3; ESI-MS:
M þ Hþ (m/z) 233.
N,N-Diallyl-4-methoxy-2-nitrobenzenamine (2r). Isolated as red oil,
1
210 mg, 85%. H NMR (300 MHz, CDCl3) d 7.12–7.16 (m, 2H), 6.98–
7.02 (m, 1H), 5.70-5.81 (m, 2H), 5.07-5.17 (m, 4H), 3.78 (s, 3H), 3.61
(d, J ¼ 6.18 Hz, 4H); 13C NMR (75 MHz, CDCl3) d 155.0, 146.5, 137.7,
134.6, 126.0, 119.3, 118.0, 108.8, 56.6, 55.9; ESI-MS: M þ Naþ (m/z) 271.
ACKNOWLEDGMENTS
This work was supported by the National Natural Science Foundation of
China (20572058) and Beijing Department of Education (XK100030514).
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